China plans to spend heavily on technology to help cities cope with headaches such as air pollution and traffic jams—and perhaps unruly mobs and outlaws. According to The Wall Street Journal, Silicon Valley companies are teaming up to seize the opportunity despite civil liberties issues, a trend that could raise the profile of players like Sensity Systems Inc. The closely held company on Friday is expected to announce a joint venture with a spinoff from China’s Academy of Sciences to help build new-wave data networks with such features as video surveillance and sensors to monitor traffic and air quality. Navigant Research estimates $174.4 billion will be spent on smart-city projects between 2014 and 2023, with China accounting for a major share.